Low-Voiding Die Attach Film, Semiconductor Package, and Processes for Making and Using Same

Abstract

This invention is a low-voiding adhesive film prepared from a composition. The composition comprises a toughening polymer, a curable resin, a curing agent for the curable resin, a void reduction compound, and a curing agent for the void reduction compound. The void reduction compound has at least two Si—O moieties contiguous with each other and at least one reactive functionality. Additional embodiments of this invention are described, including a process for producing the low-voiding die attach film, a method for reducing voids in a semiconductor package using the film of this invention, and a semiconductor package assembled with the film of this invention.

1 . An adhesive film prepared from a composition comprising: (i) a toughening polymer; (ii) a curable resin; (iii) a curing agent for the curable resin; (iv) a void reduction compound having at least two Si—O moieties contiguous with each other and at least one reactive functionality; and (v) a curing agent for the void reduction compound. 
     
     
         2 . The adhesive film of  claim 1  wherein the reactive functionality is selected from the group consisting of vinyl, hydroxyl, carboxyl, epoxy, acrylate, methacrylate, and a combination of these. 
     
     
         3 . The adhesive film of  claim 1  wherein the curable resin is selected from the group consisting of bismaleimide and epoxy. 
     
     
         4 . The adhesive film of  claim 1  wherein the toughening polymer is selected from the group consisting of CTBN rubber and a polymer comprising a backbone and pendant from the backbone at least one siloxane moiety and at least one reactive moiety capable of reacting to form a new covalent bond. 
     
     
         5 . The adhesive of  claim 1  wherein the void reduction compound is selected from the group consisting of: 
       
         
           
           
               
               
           
         
       
       and combinations of these. 
     
     
         6 . A method for reducing voids in an adhesive used in a semiconductor package comprising
 (i) providing a composition comprising a toughening polymer, a curable resin, a curing agent for the curable resin, a void reduction compound having at least two Si—O moieties contiguous with each other and at least one reactive functionality, and a curing agent for the void reduction compound;   (ii) applying the composition to a carrier;   (iii) B-staging the composition thereby producing an adhesive film plus carrier;   (iv) contacting the adhesive side of the adhesive film plus carrier to a semiconductor die or to a substrate for the semiconductor die;   (v) removing the carrier to expose the adhesive film;   (vi) contacting the semiconductor die, if the adhesive is applied to the substrate for the semiconductor die, or contacting the substrate, if the adhesive is applied to the semiconductor die, to the exposed adhesive film so that the adhesive film is disposed between the die and its substrate; and   (vii) subjecting the adhesive film to at least one thermal operation.   
     
     
         7 . The method of  claim 6  wherein the reactive functionality is selected from the group consisting of vinyl, hydroxyl, carboxyl, epoxy, acrylate, methacrylate, and a combination of these. 
     
     
         8 . The method of  claim 6  wherein the curable resin is selected from the group consisting of bismaleimide and epoxy. 
     
     
         9 . The method of  claim 6  wherein the toughening polymer is selected from the group consisting of CTBN rubber and a polymer comprising a backbone and pendant from the backbone at least one siloxane moiety and at least one reactive moiety capable of reacting to form a new covalent bond. 
     
     
         10 . The method of  claim 6  wherein the void reduction compound is selected from the group consisting of: 
       
         
           
           
               
               
           
         
       
       and combinations of these. 
     
     
         11 . The method of  claim 6  wherein the carrier is a release liner selected from the group consisting of polyimide film, polyethylenenapthalate film, and polyethyleneterephthalate film. 
     
     
         12 . The method of  claim 6  wherein the substrate is an organic substrate for semiconductor packaging selected from the group consisting of bismaleimide triazine resin, epoxy resin, and FR-4 board. 
     
     
         13 . The method of  claim 6  wherein the thermal operation is selected from the group consisting of curing of the adhesive or wirebonding of the package. 
     
     
         14 . A semiconductor package prepared by
 (i) providing a composition comprising a toughening polymer, a curable resin, a curing agent for the curable resin, a void reduction compound having at least two Si—O moieties contiguous with each other and at least one reactive functionality, and a curing agent for the void reduction compound;   (ii) applying the composition to a carrier;   (iii) B-staging the composition, thereby producing an adhesive film plus carrier;   (iv) contacting the adhesive side of the adhesive film plus carrier to a dicing tape;   (v) laminating the adhesive film to the dicing tape, thereby producing a bundled wafer backside lamination (BWBL) film;   (vi) removing the carrier, contacting the exposed adhesive side of the BWBL film to a semiconductor wafer and laminating the BWBL to the semiconductor wafer so that the adhesive film is disposed between the semiconductor wafer and the dicing tape;   (vii) dicing the wafer and adhesive into individual semiconductor dies with adhesive;   (viii) removing a die with the adhesive film attached from the dicing tape;   (ix) contacting the adhesive film to a substrate so that the adhesive film is disposed between the semiconductor die and the substrate to form an assembly; and   (x) subjecting the assembly to at least one thermal operation.   
     
     
         15 . The semiconductor package of  claim 14  wherein the reactive functionality is selected from the group consisting of vinyl, hydroxyl, carboxyl, epoxy, acrylate, methacrylate, and a combination of these. 
     
     
         16 . The semiconductor package of  claim 14  wherein the curable resin is selected from the group consisting of bismaleimide and epoxy. 
     
     
         17 . The semiconductor package of  claim 14  wherein the toughening polymer is selected from the group consisting of CTBN rubber and a polymer comprising a backbone and pendant from the backbone at least one siloxane moiety and at least one reactive moiety capable of reacting to form a new covalent bond. 
     
     
         18 . The semiconductor package of  claim 14  wherein the void reduction compound is selected from the group consisting of: 
       
         
           
           
               
               
           
         
       
       and combinations of these. 
     
     
         19 . The semiconductor package of  claim 14  wherein the substrate is an organic substrate for semiconductor packaging selected from the group consisting of bismaleimide triazine resin, epoxy resin, and FR-4 board. 
     
     
         20 . The semiconductor package of  claim 14  wherein the thermal operation is selected from the group consisting of curing the adhesive and wirebonding the package.